Achieving Building Enclosure Continuity Across Building Movement Joints Sophia B. Salah, PE and Luke A. Niezelski, PE Simpson Gumpertz & Heger, Inc. 480 Totten Pond Rd., Waltham, MA 02451 (724) 331-8743 | sbsalah@gmail.com | laniezelski@sgh.com No v e m b e r 9 , 1 0 , 1 2 , 1 6 , 1 7 , 1 9 , 2 0 2 0 | 2 0 2 0 I I BE C B u i l d in g E nc l o s u r e S y m p o s i u m S a l a h a n d Ni e z e l s ki | 8 1 ABSTRACT SPEAKERS Sophia B. Salah, PE Simpson Gumpertz & Heger, Inc., Waltham, MA Sophia Salah is a professional engineer licensed in Massachusetts and California who has practiced building enclosure engineering for over ten years with Simpson Gumpertz & Heger, Inc. (SGH). Through her work, ranging from hospitals and healthcare facilities to commercial and residential buildings, Salah has extensive experience in both the investigation and design of complex enclosure systems, including below-grade waterproofing, plaza waterproofing, roofing, opaque cladding, curtainwall, and fenestration systems. As more buildings are being constructed in complex geometries and adjacent to existing buildings, Salah works with architects and contractors to provide a continuous building enclosure across movement joints. Luke A. Niezelski, PE Simpson Gumpertz & Heger, Inc., Waltham, MA Luke Niezelski joined the building technology division of SGH in 2014. He is licensed in Massachusetts as a professional engineer and is experienced in the investigation/assessment, design, construction administration, monitoring/inspection, and field testing of historical and contemporary building enclosure systems. Niezelski has been involved in various Boston high-rise construction projects and is routinely collaborating with architects, owners, and contractors on complex building enclosure designs. Structural engineers consider movement joints as a separator or physical break between adjacent buildings (or portions of buildings), while building enclosure designers require movement joints to connect the thermal, moisture, air, and water control layers. Often architectural drawings include a premanufactured movement joint sized to accommodate the anticipated structural movement of the joint. A common challenge is understanding how the movement joint system, which often includes complex geometry, interfaces with the adjacent building enclosure systems that are being connected. The speakers will address how to detail, develop, and construct movement joint systems to maintain enclosure continuity and prevent leakage. The presented approach is based on the speakers’ combined experience investigating failed movement joints, and applying lessons learned to the design and construction of movement joints in new design projects. In this presentation, the speakers will review how movement joints fail from a building enclosure perspective and identify key details and requirements for movement joint systems that are required to maintain a continuous envelope across multiple enclosure systems. 8 2 | S a l a h a n d Ni e z e l s ki 2 0 2 0 I I BE C B u i l d in g E nc l o s u r e S y m p o s i u m | No v e m b e r 9 , 1 0 , 1 2 , 1 6 , 1 7 , 1 9 , 2 0 2 0 WHEN MOVEMENT JOINT SYSTEMS FAIL TO CONNECT ACROSS THE BUILDING ENCLOSURE Movement joints, typically referred to as seismic or expansion joints, are joints designed to accommodate movement between two independent structures. The movement joints are intended to accommodate displacements from the combination of seismic activity, wind loads, settlement, and thermal expansion and contraction. Movement joints require flashings to connect air, water, and thermal control layers and fire safing (excluded from the discussion) across various building enclosure systems. Movement joints occur below grade; in plazas; and through vertical building elevations, roofs, and interior spaces (this paper discusses exterior movement joints only and focuses on the continuity of the air and water control layers). Many manufacturers have standard movement joint flashing options and cover systems which designers can incorporate into their drawings to protect the movement joint flashings. From all these options, an appropriate joint cover and/or flashing system must be carefully selected to connect various adjacent building enclosure systems and materials together across complex geometries. This paper focuses on how to achieve exterior air/water barrier continuity across movement joints and what is required to make them work. Failure to provide this continuity can cause leakage into the occupied spaces below the joint, which often results in accelerated deterioration of the enclosure’s thermal insulation and fireproofing, as well as premature damage to structural members and interior finishes adjacent to the leaking movement joint. The following examples—one case of discontinuous waterproofing membranes at a movement joint and another case with the movement joints located at a low point in the deck— demonstrate the consequences when movement joints fail. Case Study 1: A movement joint spanned across an existing plaza consisting of (from exterior to interior): brick pavers on a mortar setting bed, aggregate base layer, protection board, sheet-applied waterproofing membrane layer one on a concrete protection slab, rigid insulation, protection board, and sheet-applied waterproofing membrane layer two on the structural concrete slab (Figure 1). The structural concrete slab is also the roof of the concrete garage structure below the terrace, and waterproofing membrane layer two was the temporary roof of the garage until the plaza system was installed. The concrete walls and beams in the garage structure below the movement joint were significantly water- and rust-stained (Figure 2). Exploratory investigation discovered that waterproofing membrane layer one and the concrete protection slab had been installed continuously across the movement joint. The waterproofing membrane layer two was deteriorated, and the concrete structural deck was discontinuous across the expansion joint. Both waterproofing membrane layer one and waterproofing Achieving Building Enclosure Continuity Across Building Movement Joints No v e m b e r 9 , 1 0 , 1 2 , 1 6 , 1 7 , 1 9 , 2 0 2 0 | 2 0 2 0 I I BE C B u i l d in g E nc l o s u r e S y m p o s i u m S a l a h a n d Ni e z e l s ki | 8 3 Figure 1 – Plaza assembly components. Figure 2 – Rust and water stains below the leaking movement joint in the plaza above. membrane layer two were discontinuous at the horizontal-to-vertical expansion joint transition as they did not extend vertically onto the parapet wall (Figure 3). The waterproofing membrane layers were poorly bonded to the concrete slabs at these discontinuities, and the slabs below were saturated, indicating that the assembly had failed. Although there were two waterproofing layers, the lack of proper detailing across the joint and at transitions in the movement joint resulted in leakage into the garage stairwell below. In this example, the building owner opted to remove and replace the entire plaza system down to the structural deck in order to address the leakage. Case Study 2: In a similar example, a plaza consisting of (from exterior to interior): brick pavers, mortar setting bed, hot rubberized asphalt waterproofing membrane, and structural concrete deck located above a parking garage had several movement joints. The movement joints were installed directly at the membrane level at low points in the structural deck and the hot rubberized asphalt system spanned continuously across the joints. The concrete adjacent to the membrane bellows was water stained and, after rain events, water cascaded from these joints into the garage and pooled on the floor. The waterproofing membrane had been compromised, mainly due to improper detailing at the perimeter of the plaza, and water flowed directly to the movement joints. A membrane bellows gutter system with weep tubes was installed below the structural concrete deck beneath the movement joints to control the expected leakage (Figure 4). The weep tubes drained to garbage cans or directly to floor drains at the floor slab in the parking garage. While the movement joints were not the primary issue with the plaza, the plaza deck sloped towards the joint. Accordingly, when the water migrated below the membrane, water was directed to the joints, forming a direct leakage path into the garage below. The amount of leakage experienced in service overwhelmed the membrane bellows gutter backup system. In this example, the building owner decided to remove and replace the entire plaza waterproofing system. ANTICIPATED STRUCTURAL MOVEMENT There are various movement joint cover systems available in the market designed to accommodate movement and provide enclosure continuity across the joint that can be used to avoid the scenarios 84 | Salah and NiezelskiKI 2020 IIBEbeC BuildINg ENClosure Symposium | November 9, 10, 12, 16, 17, 19, 2020 Figure 4 – Water staining at concrete adjacent to membrane bellows gutter below the movement joint in the plaza above. Figure 3 – Waterproofing membrane layer two is discontinuous at the horizontal expansion joint and does not extend vertically onto the parapet. described above. The options discussed below include premanufactured movement joint covers, membrane bellows, PVC or TPO accordion movement joints, and pre-compressed expanding joint seals. Benefits and disadvantages of each system, as well as compatibility to the adjacent building enclosure systems must be considered by the designer when selecting a movement joint cover. The first step in assessing joint cover system selection is to determine the size of the joint and the anticipated movement of the adjacent building components. Work with the structural engineer and other members of the design team early in the design process to define movement joint locations, sizes, and required movement capacities. Stressing the challenges and risks associated with movement joint waterproofing will help the team optimize the size, number, and location of joints. Many factors are considered when determining the size and anticipated movement across movement joints, and only buildings of a certain size and geometry will require them. A simplified overview of the governing factors and how they are typically accounted for in the design of movement joints is presented herein. The main considerations include material changes due to drying shrinkage, creep and temperature, and movement from wind and seismic loads. Stresses from elongation or shortening due to material deformation (such as from drying shrinkage and temperature changes) are generally simplified in design and considered as applied normal to the joint or parallel to the joint; however, material deformations can introduce additional stresses (including differential shear deformation) to the building structure depending on the geometry of the connecting structures and location of the structural supports. Design wind pressures and seismic loads are determined based on ASCE-07, Minimum Design Loads and Associated Criteria for Buildings and Other Structures. Alternatively, wind pressures can be determined from a wind tunnel study for buildings with complex geometry. The effect of the wind load is determined by applying the load both normal and parallel to the movement joint. The effects of seismic loads, and consequently the joint size, vary depending on building use and location. The movement joint is evaluated for seismic movement vertically and in plan both perpendicular and parallel to the movement joint while also considering the effects of torsion where required. The design accounts for potential damage to the joint from the maximum movements in all directions. The seismic design criteria for buildings and other structures in ASCE-07 depends on the project’s site class (accounting for site soil properties and seismic acceleration based on the site conditions), importance factor (Table 1.5-2 in ASCE-07), and risk category (Table 1.5-1). Additionally, depending on the type of seismic event and structure, vertical movements across the joints need to be accounted for. These movements depend on multiple factors, including soil conditions, type of seismic wave, and dynamic characteristics of the structure. Based on these considerations, essential facilities in Risk Category IV expect to see larger joints than similar buildings in lower-risk categories. For example, commercial office or residential buildings of a certain size and geometry (Risk Category II) in the Northeast typically require movement joints between 2 in. and 4 in. wide with around 50% to 100% contraction and expansion in all directions across the joint; however, a hospital (Risk Category IV) in the Northeast can have seismic joints that are as large as 18 in. wide with 18 in. of compression and expansion movement expected in each direction. PREFABRICATED METAL COVER SYSTEM Prefabricated metal covers are typically installed at movement joints at roof-to-rising-wall transitions. These prefabricated, aesthetically pleasing metal cover assemblies come in a wide variety of sizes and often include membrane bellows. An important consideration for the prefabricated movement joint cover system is maintaining continuity at transverse joints between metal cover pieces. Transverse joints need to be detailed not only to accommodate movements across the joint, but also thermal movements within the metal cover itself. Manufacturers provide factory-welded and -mitered pieces for corners and transitions. To accommodate the thermal expansion at transverse joints, some manufacturers require providing a 1/8 in. wide gap between the two metal cover pieces, setting a metal splice plate in a bead of sealant on each side of the metal cover pieces, and mechanically fastening to one side of the metal cover. One challenge with using the prefabricated joint cover assembly is maintaining continuity at changes in plane in the movement joint such as transitions from horizontal (roof) to vertical (wall) movement joints. While manufacturers offer standard pieces for typical transitions, careful review is required with the selected basis of design system manufacturer to determine where custom transition pieces are required for the project-specific conditions. These cover systems are appropriate for both horizontal (roof and plaza) and vertical (exterior wall) movement joints with minor vertical displacements because if there will be vertical movement across the joint, the metal cover can be damaged or displaced from the out-of-plane movements. A common misconception is that the prefabricated metal cover alone provides the enclosure system continuity across the November 9, 10, 12, 16, 17, 19, 2020 | 2020 IIBEbeC BuildINg ENClosure Symposium S Salah and NiezelsKI | 85 Many factors are considered when determining the size and anticipated movement across movement joints, and only buildings of a certain size and geometry will require them. joint. However, it is often very difficult to maintain a watertight cover when considering anticipated movements, complex geometries, and the inherent limitations of using a rigid material to waterproof a moving joint. To maintain continuity of the building enclosure, these covers often include a membrane gutter or “bellows” to connect the adjacent wall air/water/vapor barriers and roofing/waterproofing membranes across the joint. Some prefabricated joint cover systems include a polyethylene bellows sheet that can be difficult to cut, form, and seal in a watertight manner when the geometry of the joint is complex. Enhancing these joints by providing an alternate membrane for the bellows that is easier to cut, form, and reliably seal can simplify the installation and improve waterproofing durability at these complex geometries (Figure 5). The International Energy Conservation Code (IECC) is currently silent on requirements for thermal performance across movement joints. The movement joint should include insulation where required to maintain a continuous thermal barrier. For example, a movement joint within a roofing system should include insulation to provide some thermal value at this discontinuity in the roof deck. The polyethylene bellows sheet can be used to support insulation to provide thermal continuity at the movement joint. Alternatively, metal straps or welded wire mesh or lath can be used to support the insulation. To limit or prevent condensation on the exterior side of the interior walls behind the joint in warm weather, the joint cover system must be airtight. To prevent condensation on the interior side of the expansion joint cover during cold weather, provide insulation within the joint and prevent warm, humid interior air from reaching the backside of the joint. MEMBRANE BELLOWS FLASHING OPTIONS: 1-IN.- TO 2-IN.-WIDE MOVEMENT JOINTS This section reviews alternate membrane bellows or flashing options that can be installed at movement joints either by themselves or beneath metal movement joint covers. Waterproofing and air barrier systems typically include flashing accessory products intended to detail changes in plane, terminations, and penetrations. These flashing accessories can often accommodate smaller joints (up to 1 in. or 2 in. wide) and seamlessly integrate to the adjacent waterproofing or air barrier system. Using these accessories will limit the number of materials and transitions across movement joints and reduce the number of subcontractors installing the materials, which in turn reduces complexity and requires less coordination between trades. We summarize some of the available options below: 1. Uncured neoprene flashing can be installed across movement joints less than or equal to 2 in. wide within hot-rubberized-asphalt waterproofing membrane systems. The neoprene sheet can be integrated directly into the hot, rubberized asphalt waterproofing membrane. The joint size must be small enough for the neoprene flashing to accommodate the anticipated movement. It is recommended to place a foam noodle (backer rod) to support a convex shape across the movement joint to direct water away from the joint rather than a concave gutter shape which collects water. 2. A PVC or TPO roofing membrane can be used to form the membrane bellows across small membrane joints in PVC or TPO roofs, respectively (Figure 6). The PVC or TPO flashing membrane should be supported by a foam noodle to create a convex shape to direct water away from the joint. The benefit of using PVC or TPO includes having hot-air-welded seams at this vulnerable condition rather than relying on adhesion alone at the seams. However, PVC or TPO membranes should not be in contact with asphalt-based membranes due to material incompatibility issues, and the plastic membrane is not capable of stretching appreciable amounts, unlike other elastic materials. 3. EPDM flashing can be used to form a convex membrane bellows (supported by a foam rod) across movement joints in conjunction with various waterproofing or air barrier systems. Using the same material for the membrane bellows in the roof and wall movement joints reduces the number of materials 86 | Salah and NiezelskiKI 2020 IIBEbeC BuildINg ENClosure Symposium | November 9, 10, 12, 16, 17, 19, 2020 Figure 5 – Prefabricated metal joint cover and membrane bellows across a 2-in.-wide plaza movement joint. and simplifies the detail complexity at transitions across the joint. Careful coordination is required to prevent material adhesion and incompatibility issues between EPDM and rubberized asphalt, silicone, or other materials. This challenge can be overcome by reviewing the adjacent materials, carefully detailing the EPDM membrane transition, and using alternative air barrier materials as needed in discrete locations to allow for durable transitions between adjacent systems. EPDM bellows membrane can be used for movement joints in both barrier wall systems such as architectural precast concrete panels, which directly stop air and water infiltration at the face of the panels; and for rainscreen systems such as brick veneer, stone, or metal panel systems with a dedicated air/vapor barrier membrane behind the veneer. 4. Alternatively, if self-adhering sheet air/vapor barrier or waterproofing membrane will be used to cover movement joints in above- or below-grade walls, the rubberized asphalt self-adhering membrane can span over gaps less than ¼ in. wide. For joints up to 1 in. wide, an inverted strip of the self-adhering flashing behind the air/vapor/water barrier membrane can be used to form the membrane bellows. This method is typically used to provide air/vapor barrier membrane continuity across horizontal deflection tracks in the cold-formed metal-framed backup walls to accommodate inter-story displacement and can similarly be used to provide air/vapor barrier continuity at 1-in.-maximum vertical movement joints. If installed behind rainscreen cladding systems, the cladding panels should be installed so that they can move independently across the movement joint. 5. A silicone sheet transition membrane is another versatile option to seal movement joints in a wide variety of waterproofing and air- barrier membranes. Silicone sheet transition membranes can seal joints between aluminum curtainwall systems and adjacent wall or roof systems. Silicone transition membrane is a tough and durable sheet membrane designed to have the ability to transition directly into aluminum curtainwall glazing pockets and span gaps unsupported (Figures 6A and 6B). There are a variety of silicone sealant options November 9, 10, 12, 16, 17, 19, 2020 | 2020 IIBEbeC BuildINg ENClosure Symposium S Salah and NiezelsKI | 87 Figure 6A – Silicone sheet transition membrane at movement joint between curatinwall and brick veneer. Figure 6B – Prefabricated cover over silicone sheet bellows. available to terminate the silicone transition membrane onto various wall and roof systems. Similar to EPDM bellows, silicone sheet transition membranes can also be used to seal movement joints at architectural precast concrete wall panels or rainscreen systems with a dedicated air/vapor barrier membrane on exterior sheathing. MEMBRANE BELLOWS FLASHING OPTIONS: MOVEMENT JOINTS GREATER THAN 2 IN. Options for bellows membrane flashing at movement joints exceeding 2 in. wide include the following: 1. Premanufactured rubber strip membrane expansion joint systems can be used in roofs and plazas with a variety of traditional roof systems, including built-up roofing, coal tar pitch, modified bitumen, and hot rubberized asphalt. The rubber bellows membrane can be formed to fit the geometries and dimensions of the site conditions. Joints and seams can be seamed together by a proprietary vulcanizing process to form monolithic and elastic-seamed joints—either in the shop or on site. If the designer opts to have the rubber bellows system arrive on site pre-detailed, then coordination is required to have the manufacturer’s representative field measure all dimensions. This results in long lead times that should be accommodated for in the design and construction schedules. If the designer opts to have field-vulcanized joints, consider that on-site vulcanization is workmanship dependent and challenging. This bellows membrane is often elevated on a curb covered with overburden so that traffic does not directly bear across the flashing membrane. 2. A flexible rubber membrane supported by closed-cell foam with adhesively and mechanically attached metal flanges is available in widths ranging from 4 in. to 12 in. and can accommodate multi- directional movement in roofs, plazas, and exterior opaque walls. This joint bellows option is versatile because the metal flanges can integrate the rubber bellows to any waterproofing, roofing, or air/vapor barrier membrane system. Factory-fabricated transitions and details are available, but these require coordination early in the design to allow for field measurement and lead times. Similar to the premanufactured rubber strip membrane expansion joint system, this type of joint is often used on an elevated curb to protect the bellows from traffic. 3. Flexible-fabric-reinforced EPDM sheet transition membranes can be used to span across large joints (i.e., 18-in.-wide joints) at roofs, plazas, and exterior walls. The considerations listed above for EPDM membrane bellows at smaller movement joints are similarly applicable to this condition. These types of membrane bellows are typically used in conjunction with prefabricated metal expansion joint covers, which allow for foot traffic if the joint is to receive pedestrian or vehicular traffic. ACCORDION-TYPE MOVEMENT JOINT FLASHING SYSTEM An alternative to using a membrane bellows includes a thermoplastic, two-flanged accordion-style expansion joint flashing system. These can be used on their own or beneath a prefabricated metal cover—depending on the aesthetic desired. An advantage to this system is that the lower flange can be secured with a termination bar and directly welded to PVC or TPO roofing/waterproofing membrane. The upper flange counterflashes over the termination bar and lower flange to provide a secondary seal over the fastener penetrations. Additionally, the transverse joints and changes in plane (i.e., at roof-to-wall intersections) are factory heat welded together to form a monolithic system. The joint cover may also be used with different roof systems—rather than hot-air welding the membranes together, the membrane manufacturer’s standard flashing would be used to seal over the upper flange. This joint cover can be installed in joints up to 9 in. wide with 2-in. to 9-in. movement across the joint that is accommodated by the folds in the cover (Figure 7). Corners and changes in plane can be accommodated by prefabricated transition pieces; however, similar considerations for long lead times and field coordination is required for this system to provide factory heat welding of joints and custom transition pieces. The rigid weld does not have much movement capacity, so these joint flashings are appropriate for smaller expansion joints with one-directional movement and minimal direction changes. PRECOMPRESSED FOAM SEALS Silicone-coated precompressed foam seals are typically used at vertical-wall movement joints and some horizontal joint applications such as parking garages and stadiums. The pre-compressed foam seal is pressed into the open movement joint and expands to fill the joint. Once the expansion is complete and the foam covers the joint from end to end, a fillet bead of sealant is applied between the silicone-coated facer and the substrate of the movement joint. No additional sealants or adhesives are used to set the pre-compressed foam seal in place. This system is largely dependent on using the proper joint seal size, substrate preparation, and workmanship. Gaps have been observed between the installed pre- compressed foam seal and the substrate, forming discontinuities in the primary air/water/vapor control layer seal across the 88 | Salah and NiezelskiKI 2020 IIBEbeC BuildINg ENClosure Symposium | November 9, 10, 12, 16, 17, 19, 2020 Figure 7 – Accordion-style movement joint with double flanges. movement joint. Accelerated deterioration of the movement joint in horizontal applications can occur when water frequently ponds or flows over the horizontal joint. For these reasons, it is preferred to either provide the air/water/vapor control layer seal with a membrane bellows flashing behind an aesthetically pleasing pre-compressed foam seal (Figures 8A and 8B) or put the pre-compressed foam seal behind accordion-style joint covers for additional protection. MOVEMENT JOINT DESIGN: DRAWING REQUIREMENTS After a careful review of the building enclosure systems and the pros and cons of the available movement joint cover and flashing products, the design team is faced with a daunting task: development of design documents that will keep the building airtight, watertight, thermally continuous, vapor controlled, and fire resistant across the movement joints. The design documents should include carefully detailed transitions between horizontal and vertical systems to maintain continuity across movement joints. It is often helpful to include axonometric drawings that demonstrate the step-by-step installation procedures (Figure 9). Developing such details will force designers and contractors to work through complex transitions and compatibility issues to produce a constructible and continuous movement joint system across the building prior to getting out in the field to avoid unforeseeable delays to the construction schedule. These details will facilitate important submittal and shop drawing review during the construction phase. November 9, 10, 12, 16, 17, 19, 2020 | 2020 IIBEbeC BuildINg ENClosure Symposium S Salah and NiezelsKI | 89 Figure 9 – Example isometric sketch demonstrating continuity between roof and wall movement joints. Figures 8A (left) and 8B (below) – Vertical PVC membrane bellows flashing and a pre-compressed foam seal cover. Some considerations that should be incorporated in movement joint system design drawings include the following: 1. Elevate horizontal roof/plaza movement joints on an 8-in. curb so that they occur above the level that is exposed to flowing water. Prolonged exposure to water leads to premature deterioration of seals. In some cases (i.e., athletic turfs or plaza replacements where there is limited room for plaza overburden components), elevating the joint might be a challenge. Review joint locations with the structural engineer to see if the joint locations can be moved to another location where the curb can be provided. At a minimum, slope the structural deck away from the movement joints to avoid directing water towards this gap in the structure. 2. Never drain or provide slope to drain across a joint. 3. Pick a joint and geometry that accommodates the movement the structure will impose on it. Consider limitations on 2-D movement (i.e., 90-degree joints at building corners). 4. For transverse joints in movement joint metal covers, enhance the manufacturer’s standard detail by installing release tape over the joint, 4-in.-wide uncured EPDM strip flashing, and then the splice plate over the EPDM flashing (Figure 10). 5. Consider complex geometries. Locate the movement joint so that it simplifies the corner transitions and changes in plane as much as possible. Include project-specific isometric details at these highly complex and vulnerable conditions to define how the movement joint cover systems maintain continuity across the exterior enclosure system components. Providing sequence sketches will clearly depict the expected movement joint cover system’s configuration and establish the basis of design requirements (Figure 11). 6. Collaborate with the installation contractor as soon as is practical to determine if a prefabricated movement joint cover is an appropriate option for the project. A field-fabricated movement joint approach may be preferable for a moderately sized project with simple movement joint geometries. Field fabrication typically requires less coordination between trades and more options in materials, and it is typically more economical than prefabricated movement-joint cover systems. However, if the building connects to several adjacent structures and the movement joint will have complex geometry, a prefabricated movement joint supplied by a company that is also capable of providing design services might be better suited. Quality control in the field should be required for both prefabricated and field-fabricated approaches, regardless of the option selected. 7. Consider what the new structure will be connecting to across the movement joint. Understanding the existing construction is key to integrating the movement joint system to the existing building’s enclosure systems. This requires the foresight of performing exploratory openings in the existing structure to make informed decisions early in the design process. For above-grade joints, the exploratory openings will provide two basic pieces of information: identification of existing materials and an understanding of how the existing wall system manages water. Both pieces of information are equally important when designing a movement joint cover system. In some cases, sampling and lab testing of the materials will be required to determine their compositions so that compatible materials can transition onto the existing materials. Determining how the wall system manages water will inform the design on whether the movement joint system will integrate to a rainscreen or barrier wall. If connecting to an existing rainscreen system, the waterproof joint cover must connect to the existing structure’s air/water/vapor barrier system within the rainscreen system. This will likely require removal and replacement of portions of the rainscreen façade in order to provide the tie-in to the existing membrane. For example, in a horizontal movement joint connecting a roof to a rainscreen brick façade, intermittent sections of brick will need to be removed so that the expansion joint cover connects back to the air/water barrier behind the brick. The upper brick courses will need to be supported in a leg-and-leg fashion in order to complete this connection. If the existing structure is a barrier system, the new movement joint cover may connect and seal directly to the surface of the barrier system with the terminated edge protected by reglet-set sheet metal counterflashing or another protective seal. The existing condition and performance of the barrier system should be reviewed and verified to ensure that the existing system is watertight and does not need repair prior to installation of the new joint cover. 90 | Salah and NiezelskiKI 2020 IIBEbeC BuildINg ENClosure Symposium | November 9, 10, 12, 16, 17, 19, 2020 Figure 10 – Detail of splice plate at transverse joint in metal cover joint system. MOVEMENT JOINT DESIGN: SPECIFICATION REQUIREMENTS The following considerations should be included within the project specifications to establish quality control and design intent requirements for the movement joint systems: 1. Require product data submittals for each joint-cover system specified. This is critical as material changes can affect the design intent for the movement joint covers. 2. Require submittal of shop drawings that include project- specific details for each expansion control system specified. The shop drawings should include plans, elevations, sections, details, splice joints, blockout requirements, attachments to adjacent work, and adjacent systems that will be connected to the movement joint cover system. Details should include axonometric details (similar to those defined in the contract documents) that depict complex geometries, transitions, and changes in plane. 3. For movement joints with complex geometry, require submittal of a line diagram showing the movement joint route, and label each movement joint cover system clearly on the diagram (Figure 12). Include a schedule of movement joint systems. This can be prepared by or under the supervision of the movement joint cover system manufacturer. The schedule should include the product’s model and manufacture number for each system, nominal joint width, and anticipated joint movement in multiple directions. 4. Require the general contractor to engage the manufacturer of the movement joint cover system early. For field- fabricated joint cover systems, the manufacturer can review joint sizes and materials to confirm the design intent. For complex prefabricated joint cover systems, engaging the manufacturer early can help coordinate November 9, 10, 12, 16, 17, 19, 2020 | 2020 IIBEbeC BuildINg ENClosure Symposium S Salah and NiezelsKI | 91 Figure 11 – Example sequence isometric drawings. Figure 12 – Line diagrams demonstrating movement joint path. construction lead times and field measurements. The shop drawings should be developed based on this coordinated effort. 5. Part two of the specification should clearly identify each basis-of-design joint system and where the system is to be installed. 6. Require factory-fabricated transitions and corners by the building movement joint cover manufacturer. 7. Require the manufacturer’s technical representative to visit the site during construction of the movement joint cover system and submit a field report documenting their observations and any recommendations. 8. Specify field testing of the installed movement joint cover system using a handheld nozzle in general accordance with AAMA 502, Quality Assurance and Diagnostic Water Leakage Field Check of Installed Storefronts, Curtain Walls, and Sloped Glazing Systems, and/or perform simple water tests (no differential pressure) with a calibrated spray rack (Figure 13). Test one type of each joint system. SUMMARY OF BEST PRACTICES FOR FUTURE PROJECTS While adequate attention is often focused on individual enclosure systems, the effort means little if the systems are improperly connected at movement joints. The concepts discussed should aid in development of comprehensive design documents that will help to substantially improve the integrity and performance of the movement joint cover systems. The impact of the discussed concepts on the fabrication of adjacent systems, sequencing, constructability, and weatherproofing varies; however, the cost and scheduling impact is greatly offset by the long-term durability and peace of mind gained from a thoroughly designed movement joint system. We recommend using the following best practices to develop detailed specifications and drawings to maintain continuous and durable movement joint cover assemblies: • Review the building movement requirements, including in-service movement and seismic movement. • Understand the movement joint’s geometry. Based on this information and the anticipated movement, you can establish whether a prefabricated or field-installed expansion joint is appropriate for your project. • Trace a line across the entire movement joint on plans, elevations, and isometric views. Identify inside corners, outside corners, horizontal-to-rising walls, and other places where the geometry of the movement joint is complicated. Create project-specific isometric movement joint details at each location. Include sequence detailing where coordination will be difficult. • Confirm the proposed adjacent enclosure system. Determine the project-specific air/water/vapor barrier control layers, glazing, and opaque wall systems that will interface with the movement joint. Review each system’s transition details and determine what expansion joint materials are compatible with the systems. If incompatible materials will meet, identify these areas and begin developing specialized transition details between the incompatible materials. • Build your specifications to include requirements presented in this article. These items may need to be reviewed and revised as the development of the movement joints progresses. • Reach out to manufacturers and enclosure consultants to review and guide the design of the movement joints. Manufacturers and consultants can provide project-specific movement joint details from a large variety of past projects that may be similar to the challenge that you are facing. The experience of what has worked and what has not worked can bring tremendous value to your project. • Work with the contractors who will be installing your movement joints as soon as practical to understand the design intent, and review constructability early on to set the team up for success in the field. De-scoping meetings, pre-construction meetings, and in-place mockups are critical for explaining what the expectations for continuity and durability are for the movement joint cover systems. 92 | Salah and NiezelskiKI 2020 IIBEbeC BuildINg ENClosure Symposium | November 9, 10, 12, 16, 17, 19, 2020 Figure 13 – Handheld-nozzle water testing of installed TPO bellows membrane at a movement joint.
